Lot quantities are denoted by a number before the lot description (i.e. 5x or Qty 5). This means any bids you place will be multiplied by the quantity. All bids placed are for each item in the lot. You are required to buy the full amount at your bid price multiplied by the total quantity. The final hammer price is the multiplied amount.
The live bidding console will display the amount of the current bid and the next bid and the multiplied amount that will be paid based on the quantity.
Example: The auctioneer has 5 x Wooden Crates. They are asking for £1. This is per crate. So if you were to bid £1 then you would be paying £5.
Sometimes auctioneers will offer multiple items in a lot but you only have to pay the bid price. The bidding console will always tell you how much you are expected to pay.